backend changes on test files of catalog

tests/test_store_catalog_pipeline.py

@@ -30,6 +30,19 @@ def _sheet(headers, rows) -> bytes:
     return buf.getvalue()
 
 
+@pytest.fixture(autouse=True)
+def _isolate_sku_counter(tmp_path, monkeypatch):
+    """Keep the SKU sequence counter out of the repo.
+
+    `sku_service` persists its per-brand counter to DATA_DIR/sku_sequences so
+    reruns keep issuing fresh numbers. Left alone, running the suite mutates a
+    real directory in the working tree; pointing it at tmp_path keeps each test
+    session self-contained and makes SKU numbering deterministic per test.
+    """
+    from app.services import sku_service
+    monkeypatch.setattr(sku_service, "_data_dir", tmp_path / "sku_sequences")
+
+
 @pytest.fixture
 def store(monkeypatch):
     """A fake brand table. Returns the dict of image_id -> stored row."""